/// <summary>
/// 全局错误
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
protected void Application_Error(object sender, EventArgs e)
{
    Exception ex = Server.GetLastError();
    LogHelper.Error(ex); // 记录错误日志（NLog 挺好用的(*￣︶￣)）

    if (Context.Handler == null)
    {
        return;
    }

    if (new HttpRequestWrapper(Request).IsAjaxRequest())
    {
        Response.Clear();
        Response.ContentType = "application/json; charset=utf-8";
        Response.Write("{\"state\":\"0\",\"msg\":\"" + ex.Message + "\"}");
        Response.Flush();
        Response.End();
    }
    else
    {
        // 方案一 重定向到错误页面，带上简单的错误信息
        //string errurl = "/Error/Error?msg=" + ex.Message;
        //Response.Redirect(errurl, true);

        // 方案二 带上错误对象，转到错误页
        Response.Clear();
        RouteData routeData = new RouteData();
        routeData.Values.Add("Controller", "Shared"); // 已有的错误控制器
        routeData.Values.Add("Action", "Error"); // 自定义的错误页面

        Server.ClearError();
        SharedController controller = new SharedController(); // 自定义错误页面控制器
        string errController = Request.RequestContext.RouteData.Values["Controller"].ToString();
        string errAction = Request.RequestContext.RouteData.Values["Action"].ToString();
        HandleErrorInfo handleErrorInfo = new HandleErrorInfo(ex, errController, errAction);
        controller.ViewData.Model = handleErrorInfo; //传错误信息
        RequestContext requestContext = new RequestContext(new HttpContextWrapper(Context), routeData); // 封装与已定义路由匹配的HTTP请求的信息
        ((IController)controller).Execute(requestContext); //执行上下文请求
        Response.End();
    }
}

@model System.Web.Mvc.HandleErrorInfo
@{
    ViewBag.Title = "系统错误";
    Layout = "~/Views/Shared/_Layout.cshtml";
}

<h3 class="text-danger">系统错误</h3>
@if (Model != null)
{
    <span class="text-warning">@(Model.Exception.Message)</span>
}
else
{
    <span class="text-warning">处理请求时出错。</span>
}

public ActionResult Error()
{
    return View();
}

<!--开启会导致异常不走Application_Error,直接寻Error-->
<!--<customErrors mode="On" defaultRedirect="~/Error.cshtml" />-->